Abstract

月の地下に大量の氷が埋蔵されている可能性 --月隕石から氷の痕跡である「モガナイト」を発見、月で利用可能な水資源に期待--. 京都大学プレスリリース. 2018-05-09.Moganite, a monoclinic SiO2 phase, has been discovered in a lunar meteorite. Silica micrograins occur as nanocrystalline aggregates of mostly moganite and occasionally coesite and stishovite in the KREEP (high potassium, rare-earth element, and phosphorus)–like gabbroic-basaltic breccia NWA 2727, although these grains are seemingly absent in other lunar meteorites. We interpret the origin of these grains as follows: alkaline water delivery to the Moon via carbonaceous chondrite collisions, fluid capture during impact-induced brecciation, moganite precipitation from the captured H2O at pH 9.5 to 10.5 and 363 to 399 K on the sunlit surface, and meteorite launch from the Moon caused by an impact at 8 to 22 GPa and >673 K. On the subsurface, this captured H2O may still remain as ice at estimated bulk content of >0.6 weight %. This indicates the possibility of the presence of abundant available water resources underneath local sites of the host bodies within the Procellarum KREEP and South Pole Aitken terranes.